The Cosby Show star Phylicia Rashad is convinced the sexual abuse allegations against Bill Cosby have been "orchestrated" to ruin his legacy.

The 66-year-old actress, who starred as Cosby's onscreen wife in the TV sitcom from 1984 to 1992, is adamant she never witnessed any behaviour to suggest there is truth in the barrage of allegations the comedian has faced in recent months.

More than 20 women, including supermodels Beverly Johnson and Janice Dickinson, have accused Cosby of sexual abuse and inappropriate behaviour decades ago, but Rashad believes the scandal is part of a scheme to get Cosby off TV.

She tells Showbiz411.com, "Forget these women... What you're seeing is the destruction of a legacy. And I think it's orchestrated. I don't know why or who's doing it, but it's the legacy. And it's a legacy that is so important to the culture.

"Someone is determined to keep Bill Cosby off TV... And it's worked. All his contracts have been cancelled."

Rashad supports Cosby's decision to remain silent on the allegations, adding, "If he spoke now, what do you think the media would do with it?"

Rashad's words of support comes just days after her co-star Keshia Knight Pulliam insisted the version of Cosby described in the claims is "not the man I know".